How was the Higgs boson discovered?

Hear the story of the multi-decade trans-Atlantic rivalry that led to the Higgs boson discovery.

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Episode Transcript

Speaker 1 (00:08):
Hey, Daniel, did you celebrate July fourth? Of course, it's
a really important day in history. July fourth, two thousand
and twelves two thousand twelve. You mean seventy right, American
Independence Day? Oh? I mean, yeah, that's important too, But
two thousand and twelve was a much more important day,
more important than the founding of our country. Yeah, this
is like cosmically important, all right, I'll buy what happened

(00:31):
on July four, two thousand and twelve. July four, two
twelve is the Higgs Dependence Day. It's the day we
announced the discovery of the Higgs boson. Did we beat
the British to it? Or it was our reunion with Britain?
We did it together. Hi am Jorge. I'm a cartoonists

(01:02):
and the creator of PhD comics. Hi. I'm Daniel Whitson.
I'm a particle physicist, and the only particle I've ever
helped discover was the Higgs boson. Oh nice, I've discovered
lots of particles. There's plenty of dust particles in my house,
none of which are particularly interesting. Some of them are big,
but not Higgs. But welcome to our podcast. Daniel and
Jorge explain the Universe, a production of I Heart Radio

(01:23):
in which we talk about all the crazy and amazing
things that we find in our universe. We take you
to the forefront of knowledge where scientists are trying to
figure out how everything works, and we show you how
you can understand it to how your curiosity is the
same as theirs. Yeah, and we like to talk about
not just the things that scientists discover and what we
understand about them, but we also like to talk about

(01:45):
how they were discovered because we think this it's a
very important part of understanding science and how science works,
and what science knows and what it can know. That's right.
Sometimes particle physics is presented is like a grand edifice
that we've put together all at once, But really it's
sort of like a sloppy house of cars that we've
been building bit by bit over the last hundred years,

(02:06):
and each piece was added painfully and with great effort
due to lots of theorists and experimentalists working hard. And
usually there are fun, juicy political dramas along the way.
I guess it's made out of particles, the house of particles.
Everything's made out of particles. Man Or Field, you did
a TV series called House of Particles. There's definitely enough

(02:26):
drama in particle physics to fuel a whole soap opera.
Hopefully nobody gets pushed into a train or anything like that.
But more than that, we want you to understand that
this idea of particle physics, these things that we understand,
are not just some theoretical concept, but they're slowly built
up from actual discoveries, experiments. We've done, things that we
forced the universe to reveal, and it's those experiments, those

(02:48):
actual discoveries, those confrontations with nature that formed the foundation
of that understanding. Yeah, because I think it's easy, once
you know something to just forget that you at some
point didn't know something. You know, like, think back when
you're a kid and you didn't know about the universe
or galaxies or planets. What were you thinking, Like, what
was your view of the world. That's right, Like, before
I knew that bananas were gross, I thought like, hey,

(03:10):
maybe they were okay, But now I can never go
back to a universe in which bananas could be digestive.
Hey more bananas for me, Man, Mandy that you don't
like them, it all works out, But you know, sometimes
I like to imagine like alternative universes in which discoveries
were made in different orders and different things were weird
or puzzling, because you know, the reason that things seem

(03:30):
weird is only because we haven't seen the whole picture.
It's like when you're doing a jigsaw puzzle and you
don't know like where these pieces go or what's that's
going to reveal. The nature of the questions comes from
the past you haven't found yet, But in some sense
that's just due to luck. You know, we found this before,
we found that, We stumbled over this before we stumbled
over that. So the history of these discoveries is really
important for you to understand why we're asking the questions

(03:52):
we're asking now. Yeah, so to be on the program,
we are covering some pretty recent history of physics wise,
and we're probably the most famous particle I think in
culture these days and maybe in physics. That's right, and
that's not something I'm grumpy about. I mean, I think
the Higgs Boson deserves its role, is the most famous particle.
It plays a really a central role in our theory,

(04:14):
and it's a really epic struggle to find it. The
search for it goes over many billions of dollars and
many different particle colliders and many decades. Yeah, so to
be on the program, we'll be asking the question, how
was the Higgs boson discovered on a Tuesday? Right, wasn't
it or a Wednesday? You know, it was no single moment.

(04:38):
I think that's the short answer to the question. It's
not like we came into work one day and boom,
there was a Higgs boson in our email inbox. You know,
We're like we found one in the center of the lab,
or there was just one moment when the results were
like boom, there we have it in sort of a
slow build, the gradually accumulation of data, a very gentle,
gradual reveal, not like an exciting plot twist at the end.

(05:01):
I guess it wasn't discovered with the bang. It was
more like with twenty three Brazilian bangs. A second. It's
like somebody very slowly drawing back the curtains so you
can see more and more and more of the drama
builds slowly, but then you know you need to have
a date. You need to have a moment where you say, okay,
this is it. We've decided we've discovered it, so that's
officially the moment of discovery. You guys picked your life four. Yeah,

(05:25):
that's just sort of random, just so a fun coincidence.
And that's why we get to call it Higgs Dependence
Day because we depend on the Higgs. I guess we
all depend on the Higgs. Really, the whole universe depend
on the The whole universe does totally depend on the Higgs.
If it wasn't for the Higgs boson, our universe would
be totally different. And also, the Higgs boson is sort
of precariously balanced. It's in this weird high energy state,

(05:46):
and it's the reason that particles have certain masses, and
if that changed, then the universe would totally change. It
would collapse into something unrecognizable to us. So thank Gosh
for the Higgs boson doing what it does. He's saying
it rules by fear. We must more worship, but otherwise
it's gonna have destory the universe. I think the Higgs
boson would rather be feared than loved. Yeah, it should

(06:09):
be called the Machiavelli particle, not the God particle. All right, Well,
it's a very important particle and it was discovered recently,
and there's a bit of drama about it and a
lot of interesting twists of the stories. So we'll get
into that today, but first it's usually we were wondering
how many people out there had heard of the story
or know about the details of how the Higgs boson
was discovered. That's right, So I asked people to volunteer

(06:32):
to answer random science questions on the Internet, not knowing
anything about what I would ask them, and no googling
allowed to Thank you to everybody who participated, and if
you'd like to volunteer your voice for future random science questions,
please write to us two questions at Daniel and Jorge
dot com. All right, so before you listen to these answers,
think about it for a second. What do you remember

(06:53):
about July fourth? Here's what people had to say. The
Higgs boson was discovered, You thing the lhc um some
sequence of particle the case was detected that backed up
the theory existing on the Higgs. I know where its
cern large hydron collider, but how most likely shooting and

(07:19):
colliding particles of the Higgs boson was discovered in the
large HYDRONI the Higgs boson was predicted by Peter Higgs
and others, and then it was discovered in two thousand
twelve in the Large Head Dround Collider. It was discovered
in the Large Hadron Collider, and it was by zooming

(07:39):
around hydrogen or helium electrons very close to the speed
of light. I think it was discovered with the Large
Hydron Collider, But as to how, I don't know. I
know that Higgs boson first discovered. In theory, we knew
that every force has an acting party ill and for gravity,

(08:02):
we called that particular Higgs. Physicists, even someone like I'm son,
figured out that there was something missing, and they kept
looking forward, looking for and it was my understanding that
Higgs was the one that came up with the idea
of how it might might exist. If the Higgs boson

(08:25):
gives mass two particles, I'm going to suggest that they
started with a particle with known mass. I think I
heard in one of you guys podcasts that they were
discovered by the Large Hadron Collidas, so I'd assume that
tell it was discovered. I'm not sure, though, I feel
like I should know that one, and I think maybe
we were smashing some particles together and found some extra

(08:49):
energy that we couldn't account for. All Right, some pretty
knowledgeable answers here. You guys did a pretty good job
of educating the public. Yeah. I think it's also a
good pr by the LHC team because it's sort of
the particle collider that's in people's minds. I mean, I
don't know if you remember where we also asked people
how the top cork was discovered, and the answers were
basically the same by the Large change on collider, even

(09:11):
though that one was actually discovered by the previous collider.
So I think that this is a win for the
l a C as being the particle collider that's in
the forefront of people's minds and the tips of their tongues.
You're like the Kleenex of physics experiments. You know, pretty
soon they're going to call all colliders. That's right, I
blow my nose in the LHC. Alright, So let's step
us through the history here, Daniel. We're going to get

(09:33):
into how it was discovered and how can we know
that it's actually there. So take us back to before.
What do we know and why do we think the
Higgs boson existed? So The Higgs boson is one of
these particles that has a long history because we thought
it existed before we discovered it. There are a lot
of people who suspected it was there, and there is

(09:54):
a grand tradition of this and particle physics of like
looking at the patterns of the particles that we see
and seeing something missing, or you know, not having a
question answered and finding a missing piece that answers that question.
It's just like with the jigsaw puzzle or with the
periodic table, if there's a hole in the periodic table,
you wonder like, why is that hole there? Wouldn't this
make more sense if there was something else there. So

(10:16):
people spent a lot of time thinking about the patterns
of the particles that we had seen and wondering about
some things about them they didn't understand, and using that
to predict the existence of this Higgs boson and also
this Higgs field. But in this case wasn't really a
pattern because I know, for the like some of the
other courts, it was sort of based on a pattern,
But here wasn't it more like about the math and

(10:36):
looking at the equations and like, oh, it's missing some
field here to make it all balanced out. Yeah, Actually
it was a lack of a pattern. You see, in
the second half of this last century, people had understood
that there was a deep connection between electromagnetism, you know,
thing responsible for electricity and magnets, and the thing that
gives us the photon, and this other force, the weak
nuclear force, the one responsible for radioactive decay, and that

(11:00):
force has three particles, a Z particle and two W particles,
and people that understood that actually these two different forces
were just parts of the same force, the electro weak force,
and the photon belonged with sort of a gang. It
was actually not just like one photon over here and
three week particles over there. They're part of this gang

(11:20):
of four particles. And mathematically it fit together beautifully. It's
just like a missing part of the jigsaw puzzle finally
clicked into place and you could understand why things look
the way they looked. It was just really gorgeous. Like
from the group theory point of view, it satisfied lots
of symmetries, but there was one problem. The problem is
that the photon is really different from these other bosons

(11:43):
in an important way that you mentioned, and that it
has no mass, whereas the other ones are really heavy,
And so what made us think that they were all
together in a gang? You know, like, is it because
they all transmit the same force kind of or do
they behave in a similar way. They do kind of
behave in a similar way. I mean, electrons very familiar particles.

(12:05):
They like to interact with photons, but also with the
weak bosons, the ws and disease and that's it. Electrons
don't interact with anything else. That's all they interact with,
and so it feels sort of natural to connect all
the particles that electrons and also muons and taws talk
to and look for a pattern among them to see
if they fit into like a larger grouping. It's like

(12:27):
when you put electricity and magnetism together. Electricity is a
bunch of different phenomena that you observe and magnetism are
a bunch of different phenomena that you observe. But you
notice that sometimes electric charges cause magnetism and sometimes magnetism
can induce electricity, and so it makes more sense to
think of them as one thing. I mean, there are
different phenomenon, right, It's not like magnets are electrical, but

(12:51):
there really makes more sense. It's simpler just to think
of it as part of a larger combination. The Yeah,
it's like they're two sides of the same coin. And
so you get this beautiful connection if you plug the
photon in with these other three particles in the same
way as if you merge electricity and magnetism, you get
these beautiful symmetries. And particle physics is all about symmetries,

(13:12):
about finding these patterns. And we don't know why the
universe has symmetries. We don't know why it has patterns,
but we have found that when you look for patterns,
typically those things are clues there, hints. They show you
how the universe works, Like everything needs to do somehow
balance together, or it would be weird if it wasn't symmetry. Yeah, precisely.
And here we have a really beautiful symmetry electroweak symmetry.

(13:35):
These particles all fit together in this really nice way.
And specifically you can like rotate your way through this
four dimensional space. You have four particles there. If the
symmetry works, you can rotate between them. And so like
the photon and the z should play the same role,
you should be able to rotate between them. But the
problem is the symmetry was broken. It didn't quite work
because the photon is very very light as no mass,

(13:58):
and the z was very very heavy. So it's like
an almost symmetry. It's like it's like a hint, like
this almost works, but what about this one piece and
that piece sort of stuck in physicist I for a
long time. It's like looking in the mirror and it's
seeing kind of a different image of yourself. You're like
something's going on here, yeah, and it's like almost right,
but not quite. And so they wanted to understand, like

(14:20):
is this symmetry just flawed and we throw it out
the window, or is there a reason why it's broken?
Is that a clue? Does that explain something else? Because
the symmetry was too good to abandon, you know. On
the other hand, there's lots of times in the history
of physics when we thought we've had a beautiful idea
and had to throw it away because it just didn't work.
Like mathematically it works, but nature says no. So sometimes

(14:41):
that happens. But sometimes you know, it's just a clue
that like you need to refine it or tweak it
or twist it. And so that's what the Higgs boson was.
It was a refinement of this theory to help it work. Right,
Although I feel like it's weird because I feel like
you physicists started wanting things to be symmetric, but nowadays
they accepted some things are not symmetric. Yeah, well, you know,

(15:01):
the universe doesn't know is obey these symmetries. You know,
we'd like to see symmetry because it's like beautiful and pretty.
But then the universe says, yeah, that's nice, but I
don't follow those rules. And so then we got to
figure out why, like what are the real symmetries, you know,
or how do we break these symmetries in the smallest
possible ways? So our theories are still pretty right, I guess.
I mean, like we had known back then that some

(15:23):
symmetries can be broken, would you still have looked for
the Higgs boson or come up with the Higgs boson
or would you have just said, oh, well it's not
to meat. That's a great question, I think. So, I mean,
there's just so much evidence that suggests that the weak
force and electricity magnetism are connected. You have to find
some way to connect them. So I think it's too
tempting to avoid, So okay, So then that's how they

(15:43):
came up with the Higgs field. It's like, hey, let's
put a number here to make it all balanced out,
and let's call that the Higgs field. Yeah, because you
can't just say I'm gonna make these particles massive, I'm
just gonna put in by hand some numbers and make
the W and the Z massive because that breaks the
kind of symmetry that you're trying to protect. It's called
the local gauge symmetry of electroweak symmetry lets you rotate

(16:04):
these particles between themselves. So if you put the masses in,
it just breaks that symmetry. So they found another way
to give these particles mass. It's like, don't put the
mass on the particle itself. Instead give it mass from
its environment. So the mass is no longer like something
that belongs to the particle itself. It's an after effect.
It's an emergent phenomena from interacting with its environment. Like

(16:27):
maybe it doesn't come from the photon, but maybe there's
just something about space or the universe that somehow we're
not seeing. But magically balances out the equations. Yeah, we
talked about this on another podcast about renormalization. How for example,
the actual charge of the electron all by itself is
like negative infinity, and it's only an interaction with the

(16:47):
complex vacuum of space that it gets brought up to
minus one. And in the same way, the masses of
these particles by themselves, like the Z and the w
all by themselves and an empty universe would have mass zero,
but you put them in our universe with a complex
vacuum with particles and fields, whenever they look like they
have this heavier mass, and that's because they interact with
the Higgs boson. So it's a clever way to effectively

(17:10):
give mass to these particles without actually putting it on them,
so you don't break this symmetry. It's like a clever
little mathematical trick. I guess the idea is that it's
not a property of the particles, but it's more like
a property of interacting with something, and that's different. That's different.
Although all we can do is measure our interactions, and
so it's a bit of a philosophical difference, Like we

(17:31):
talked about in the case of the renormalization episode, like,
what does it really mean for the particle to have
no mass in an empty universe. It's never gonna be
in an empty universe. It's always going to be in
our universe. And so it's a bit of a mathematical
philosophical distinction, but it lets us keep this symmetry because
we think the symmetry deals with like the bear the
pure particle by itself. All right, pretty cool. Let's now

(17:53):
get into how we actually found this magic or not
magic particle that gives everything mass and what the search
for it was like. But first let's take a quick break.

(18:17):
All right, Daniel, we're celebrating Higgs Dependence Day, the day
that we learned of our deep dependence on the Higgs boson,
which was July four, a little over eight years ago.
So how do we actually find this Higgs boson. It's
important to understand that the first idea was not for
Higgs boson, but for Higgs field. This is some new

(18:37):
quantum field that fills the universe and has this effect
that gives the Z and the W mass and not
the photon. But one prediction of the field is that,
like all other fields, if you give them a little
blob of energy if you excite them. If you get
a little packet of excited field, then that looks like
a particle. So there's a prediction also for a new particle,

(18:57):
the Higgs boson. So the field and the part cool
have the same relationship as other particles and fields. But
what we found was not directly the Higgs field. We
look for the Higgs boson, which is the particle from
that could could you have a field without a particle,
could you know, think the Higgs field but not the
Higgs boson, or when you predict the Higgs field, you
automatically predict the Higgs boson. Well, that's a great question.

(19:20):
I think that every quantum field has to have a particle.
I can't think of an example of a quantum file
it doesn't have a particle, and I think that your
interaction with it in terms of perturbation theories always described
in terms of particles. But you know, I'm not sure
that's a that's a really fun question. We'll smoke some
banana peals and think about that deep question someday. But
I guess it was. So it's all sort of together,

(19:41):
like when Peter Higgs came up with this idea of
like playing this in to make the equations, where he
must have known right away that meant that there was
a particle involved too. Yes, absolutely, and you know, Peter
Higgs sort of wins the race to get his name
put on this, but there were lots of other people
coming up with very similar ideas at the same time,
and they submitted papers like within weeks of each other,

(20:03):
and so there's still a lot of bitterness. And in
some parts of the world it's not called the Higgs Boson,
it's called the b. E. H Boson because there's two
other guys, Brout and Englert, who have their names on it. Also,
so depending on like where your conference is, it's called
the b. E. H Boson or the Higgs Boson or
really you have to like code switch when you go
between conferences. Yeah, precisely. And there's a whole group of

(20:26):
Americans who are totally left out of the Nobel Prize
and the naming and they're grumpy and all their friends
call it after them, and so yeah, you totally have
to switch. Oh man, But you know, I like the
Higgs name. I feel like it's better than you feel
like it best sounds like you burped or something, right, Yeah,
but Higgs sounds pretty well if I'm insulting like all

(20:48):
of Europe right now, mostly just Belgium. Actually, well they
don't get insulted, so they're just drinking Belgian. Well, they
have good fries and waffles anyway. So what we do
is we look for the boson, not the field, And
like with other particles, the way you make it is
you use a collider and you smash particles together to
try to make enough energy in a tiny little spot

(21:09):
that the universe can make heavy particles. Most of the
universe is like dilute and cool, and so there isn't
enough energy to make anything except for very light stable
particles like electrons and quirks that we're made up. But
if you want to find new stuff, you've got to
collide particles that really high energy and create those little
packets of energy. The nature can then turn, sometimes very rarely,

(21:30):
into an excitation of the Higgs field and give you
a Higgs boson. I guess one question I have is,
you know, it seems like the Higgs field is so
pervasive and so integral to all particles, and it's like
it's always there, Like, why is it so hard to
make it BLib you know, Like, if it's right there,
why does it have such a big threshold for us

(21:51):
to find it. Why couldn't we have found it earlier
with lower energy collider. Yeah, that's a great question, And
the key is the mass. The prediction from Peter Higgs
was there is this field, and therefore there is this particle.
But he couldn't predict what the mass of that particle was.
It could have been very very very light, in which
case it would have been discovered just a few years
after he predicted it, or it could have been super

(22:12):
heavy so that we hadn't even discovered it yet, And
so he didn't know how heavy it was. And like
with all things in collider world, the heavier it is,
the more energy you need to make it, and so
the bigger your collider has to be, and so the
more expensive it is, and so it just took time
to build a big enough collider to find it. I
guess you need energy to make it, but I guess,

(22:34):
you know, it's sort of a weird thing to think
about the Higgs boson having mass, because isn't isn't that
what it does to give mass to things. Yeah, it's weird.
It also has self interactions and interacts with itself, and
that's the thing that gives it mass. And Higgs field
didn't predict how strong that self interaction would be, and
so we didn't know, and so people started looking for
pretty much right away and not finding it all right,

(22:58):
So then, yeah, you build a collider. You've smash protons together,
and you hope that a Higgs comes out every once
in aime, that's right, And protons have inside them quarks
and gluons. The gluons hold the quirks together, and which
you hope for is two of those gluons actually collide
together with enough energy to give you a Higgs boson.
And the Higgs boson doesn't last for very long. So
you can't just like take a picture of it. You

(23:19):
can't see it and say, here's our Higgs boson, in
which case you only would have need to have made
one of them and you could put it on your
wall and that's your discovery. The problem is that it
lasts for ten to the minus twenty three seconds and
then it turns into other stuff. That's what you gotta
do is look at that other stuff and figure out
if it looks like it came from the Higgs boson
or something else. I guess what made you think that

(23:41):
it could even had mass? Like, couldn't have been like
a photon or would that not help you with the
symmetry of the equations. Yeah, in order to have the
effect that it has, it has to have a non
zero mass, otherwise it wouldn't have this weird symmetry breaking effect.
But we didn't know it could have been ten times
heavier than it turned out to be, were ten times lighter.
You know. That's one of the frustrating things about the

(24:03):
theories that we didn't quite know where to look. And
that means you don't know how big to build your
accelerator or how it will decay, because all those things
change based on how heavy it is. Really, it can
have any kind of mass, Like you know, what, do
we have a very different universe of the Higgs boson
was really big and massive. No, you could have the
much heavier Higgs boson and basically have the same universe. Really,

(24:23):
like if the Higgs was really massive, would in that
I don't know affact how things have mass or anything
like that, because it doesn't matter most things get massed
through their interaction with the field. It doesn't matter how
heavy the particle itself is, alright, so they're really fast collisions,
and the Higgs doesn't last for very long. So how
do you actually detected, Like, how do you know it

(24:44):
existed if it only exists for ten to the minus
twenty three seconds, and so we can never say for sure.
What we do is we look at a collision and
we look at the patterns of the stuff that came out,
and we say, okay, this looked like this collision had,
for example, two photons in it. We can add up
the energies of those photon and say, okay, the total
energy that came out of this collision, how much was it?
And if higgs boson was there, then the total energy

(25:07):
that came out of the collision should add up to
the mass of the Higgs boson. So we look for
a lot of events like that, a lot of collisions
that turn into two photons. We add up all their
masses and we make a plot of it like a histogram,
and we look for a bump. We look for a
bunch of collisions that led to photons that all have
the same mass. Because if the Higgs boson is real,
it will make more of those events happen. And you

(25:29):
have to know for sure that those two photons couldn't
have come from any other thing. We can never know
that for sure. There are other ways to make two
photons photons, two same photons, but they don't tend to
make two same photons that add up to the Higgs mass.
They tend to make random masses. And so the background,
the things that mimic your signature that also give you

(25:49):
two photons, just give you random numbers. Whereas photons that
came from the Higgs always end up at about the
same place. So if you do it often enough, you
notice like a pile of them accumulating at this place.
With the true mass of the Higgs, you look for this, basically,
this bump over this background spectrum, right, and I imagine
you see other bumps, but they're probably due to other
like interactions. Right. Yeah, Well, bumps are pretty exciting because

(26:11):
they almost always mean some particles. There are some heavy
particles there and it decayed, and so basically every bump
is a Nobel prize. You know. It's sort of like
you're draining a swamp and you're seeing features in the lake,
and everyone is something fascinating and interesting. And the bigger
you're collider, and the longer you're running, the more you're
able to like pump water out of that lake and
see all the hidden features. And so we're constantly doing

(26:34):
this way. This is why we run the collider over
and over and over again, because we're looking for smaller
and smaller and more subtle bumps. The more collisions you make,
the more you can see these little bumps emerge from
the fog. So I guess it's all statistical, right, because
you you run us a bunch of times, I mean,
and if you see it's kind of like an unexpected
high incidence of you know, collisions in this mass range,

(26:56):
that must mean that the Higgs was there. Yeah, it's
all statistical, and we can't point to one event and
say this one was definitely a Higgs. We just say, well,
these fifty events all have about the same value, and
there's more close to this value than any other value,
and so we think it's very likely that it's there.
But it's a little bit frustrating because you can't like
take a picture of it or say conclusively this collision

(27:18):
was a Higgs Boson. It it's in the end of
purely statistical thing. You only see the leftovers or the
footprints in the snow. You never actually like take a
picture of it. Yeah, it's like you're looking for Bigfoot
and you have tracks, and you have spore and you
have you know, lots of other evidence that convince you
that it's not just random nonsense, but you don't actually
have the Bigfoot itself. You see a lot of poop

(27:41):
in one place that more than usual, you're like something,
something was here, and something likes to keep coming back here. Yeah, precisely.
All right, Well let's get into now how we actually
founded and what that discovery meant. But first let's take
another quick break. All right, we are talking about the

(28:10):
discovery of the Higgs Boson, which was an important date
in history, at least physics history. And step us through Daniel.
What was it actually like to like look for this
thing and to find this thing where people confident they
would find it or was it kind of a big
shot in the dark. It was a very long and
sometimes painful process, full of excitement and disappointment, and it

(28:32):
was another one of these transatlantic rivalries where the Americans
took the lead, and then the Europeans took over, and
then they didn't find and then the Americans took over
again and had a chance, and then finally the Europeans.
Really like a race, Yeah, it really was. It's like
an arms race in science, and it's constantly this like
race for who's got the highest energy colliders. It's a
bit of like nationalism and prestige. It's a lot like

(28:54):
the space race, you know, except without the threat of
i cb MS raining down on you who had the
biggest rocket kind of yeah, and it started with the Americans.
So there's a long history of looking for the Higgs
boson a very low masses and other colliders which didn't
see it. But once we understood like this thing was
going to be pretty heavy, we knew it needed a
big collider. And so the Americans had a big idea.

(29:14):
They were going to build the super Conducting super Collider,
awesomely named and it was gonna be the most powerful.
I thought you were just using iproberly, No, they used
hype of beliefs. Actually call this what is this super
super conducting super collider. It's a pretty supername. It's like
we made Superman. We're gonna we're gonna use super as

(29:36):
much as possible, exactly. And this thing was going to
have so much energy. It was going to have thirty
three Tara electron bolts. Now Tara electron bolts, it's thirty
three trillion electron bolts. That's a whole lot of energy.
And it was gonna be the biggest collider ever. And
they started building it. It was gonna be in Waxa Hatchie, Texas,

(29:58):
and they started building it. They started wearing a hole.
They cut like twenty kilometers of tunnel underground in Texas.
They spent billions of dollars, and then they canceled the project.
What happened? And well, and this one is interesting because
it wasn't a ring, right, like I think it's like
a straight collider. Now, this one was going to be
a ring, but they never finished the ring. But it's
still like a partial tunnel underground in Texas. And it

(30:22):
just sort of lost political support and became a scapegoat
for like, you know, excessive government spending, Like what are
you spending five billion dollars on this thing? Is ridiculous?
We scoffed at five billion dollars for the search for
the ultimate particle I know. And it was especially ridiculous
because they spent like two billion dollars digging a hole
and then like another three billion dollars like closing up

(30:44):
shop and filling it in. So there was so much
waste of money. And there's a funny story there because
the guy who was the director of CERN at the time,
and CERN was preparing to build their own collider to
look for the Higgs Boson, he came to the US
and testified in front of RIS that it was a
big waste of money to build the super conducting super
collider because by the time it's finished, CERN would have

(31:06):
already discovered the Higgs Boson. Sabotage. So Carlo Rubia, the
same guy who in the top Cork history made that
false claim to discovered the top word, he's sabotage. He
totally knife in the back to the super conducting stugree
with his confidence. He's just like, I don't even bother.

(31:26):
He like totally psyched us out. He totally plucked us out.
And of course his prediction with Bologna, because the Europeans
didn't discover the Higgs boson with their next collider. And
it's such a tragedy because that collider would have taught
us so much about the universe. Thirty three terror electron
bolts is three times as powerful as our best current collider,
the large Hadron collider. This is like better, even better,

(31:50):
three times better than the one we have now thirty
years ago. So particle physics was set back like several
decades by that funding decision because of this on moved
by this person who had ambition to be the first
one to discover it. Yeah, and you know, also the
vaguaries of American electoral politics and shifting priorities in the
house and all this stuff. But you know, it was

(32:12):
sort of like particle physics aimed too high and flew
too close to the Sun and then came crashing down.
I see, like maybe they had only spent two billion
dollars for twenty two tera electronic wal collider, maybe they
would have made it through. Maybe. And you know a
lot of people left their positions at academia to go
work for the super conducting SuperCollider Lab, and their careers
greater after that. And so it was really a big

(32:33):
tragedy for American particle physics, all right, so then then
the Europeans took over or what happened, Yes, and then
the Europeans took over, and the super conducting super collider
was going to collide protons, and protons are very powerful,
but the Europeans took a different strategy. They decided to
collide electrons and positrons. And these things are much cleaner
because they don't have the strong interaction, and so the

(32:55):
collisions are just simpler and more powerful and easier to understand.
The trick is not as easy to get them up
to high speed because protons are easier to accelerate to
high speed because they have more mass. Counterintuitively, right, but
this is still not This is not the LC. It's
the l EP, the Large electron positron collider, call it LEPP.
And this thing was like much much less than even

(33:17):
one terra electron vault. It was zero point two is
a fifth of a terra electron bolt. Doesn't sound so
big compared to thirty three. Yeah, exactly. It was much smaller.
But you know the good thing about having electron colliders,
you got to use all the energy in the electron.
When you collide protons, you only get part of it
because you're really just using like one cork or glue

(33:37):
on inside the proton. But when you collide electrons and positrons,
you get all the energy, so you don't need as
much energy in an electron positron collider. All right, Well,
i've never heard of the LP, so I'm guessing it
didn't discover the Higgs boltson. It didn't, but it almost did.
And they turned this thing on and they ran it
for a while and they didn't see the Higgs, and
they didn't see the Higgs, and they didn't see the Higgs.

(33:58):
And then the last summer that they were and have
this thing turned on the summer of two thousand, they're
supposed to shut down so they could tear it apart
and build the Large Hadron Collider. There's gonna be the
big upgrade. That last summer is in the same place,
in the same place, in the same tunnel, right, So
this same tunnel where the Large Electron Proton Collider was
is the same tunnel we use now for the LHC.

(34:19):
So you couldn't run both of them at once. Oh what,
there's the same size tunnel, same size tunnel, just stronger
magnets and so that's how they saved a bunch of
money to build the LHC is that they put it
in the same place as the original collider, but that
meant that they couldn't operate both at the same time.
So to build the LC they have to turn off
the l E. So what happened right before they closed? Yeah,

(34:41):
so right before they closed. It's a summer of two
thousand and you know in Europe, in like July and August,
everybody goes on vacation. It's ridiculous. It doesn't matter what's
going on. Everybody takes like a month of vacation. Month
I've heard of six weeks is the normal, and you're
a month of the minimum. Every just sort of like
slides down the continent to the beaches on the mediterrane Union.
And so some people stayed behind, didn't take vacation. And

(35:04):
a good friend of mine, Maroumi, who was a post
doc in the time, he was there in the control
room and it was like the last few weeks this
collider would even run, and he's sitting there looking at
the data, and all of a sudden, boom, there's a
collision that comes in that looks exactly like a Higgs Boson.
It's like beautiful, it has exactly everything you would expect.
It's gorgeous. You know. It has a certain mass at
about a hundred and fifteen g ev, which is like

(35:26):
right on the edge of what the L e P
could discover. And he thought, wow, that's pretty, but you
know whatever, It's one event, and then later that same afternoon, boom,
there's another one exactly the same mass, and he's like, wow,
maybe this is like the moment, Like I'm here by myself,
everybody else is on vacation. Maybe like nature is talking
to me with an incredible moment for him, why would

(35:47):
it start now and not before? Well, they were turning
up the energy, so they were cranking up the energy
bit by bit. They were like squeezing out as much
energy as they could, and so it might be that
they had just crossed the threshold to be able to
create it, right, And was it real? It turned out
it wasn't real, but it was tantalized. It was not
it was not. And in the end he had six events.
So everybody came back from vacation. He was like, guys,

(36:09):
while you were on the beach, here's what I found.
And he showed these events and it's set the whole
community on fire. People are like, oh my gosh. The
problem was they didn't have enough events to prove it.
They didn't have like conclusive evidence that had a hint, right,
So they wanted to run longer. But then everybody's also
waiting to build the LHC. So they petitioned to the

(36:29):
management of certain They said, please delay the LHC and
let's run this collider for another six months or another
year to get like conclusive evidence, right, just to get
more hits. Yeah, because across the pond, the Americans were
building their collider, the Tevatron outside Chicago, and if they
turned off the l A P would take them, you know,

(36:50):
eight or ten years to build the LHC. In the meantime,
if it really was there a hundred and fifteen, the
Americans would find it. And so it seemed like a
really dangerous bet turn off the l EP where you
had this like exciting hint that maybe it was right there,
and to build the LHC. So they actually turned it off. Yea.
They said no. The certain director said no, I don't
think that the evidence is conclusive, and the LHC should

(37:12):
be our priority, and so he shut it down. He
gave them like an extra couple of weeks and he
shut it down. What did they find in those extra weeks?
Not much. You know, they had four experiments around the
ring at the l e P and the one that
my friend was on saw six events that looked like
a Higgs boson, and a couple of the other experiments
saw one or two, but some of them saw nothing,

(37:33):
and so it was like it was tempting, It was tantalizing,
but it wasn't really that strong. It was sort of
like a last ditch effort to maybe maybe see it there,
but it wasn't really conclusive. And so the certain director
made a really tough choice, Well what do we think now,
do we think that it was or that it wasn't
for sure? We think it was just a fluctuation, because

(37:54):
if it was there, if it really was the Higgs
boson at a hundred and fift g V, the tevatron,
the neck accelerator would have found it. And now, of
course we know with the benefit of history, that's not
an hundred fifty. It was found later at one. So
that was just a fluctuation, you know, you flip a
coin a hundred times. Sometimes you'll get weird distributions, and
and that's what happened here. And the folks were like

(38:15):
desperate to find that. They were so excited to see
it that they got really excited about what, in the
end was just a few random events. All right. So
then I guess while they were building the L A C.
Then the Americans had kind of like this window for
them to do it, to find it with the teletron. Yes,
so we built a collider outside Chicago at Fermulab and
it was colliding protons and anti protons at two TV,

(38:37):
so there's ten times the energy of the collider at left.
Although you don't get to harness all that energy because
remember the proton is like a bag of particles that
has corks and gluons in it, which you're colliding are
those corks and gluons, They don't have the full energy
of the proton. But still it's really powerful, and you're right,
they had like ten years to look for it. But
you know, protons are messy because you're colliding a whole

(38:58):
bag of particles and it makes a big, messy splash,
just not as clean and pure as colliding electrons and positrons,
so it's harder. So they had more energy, but it
was always going to be tough for the tevatron to
find it. The only chance they had is if it
was very very light, if it was at one fifteen,
they could have found it, but not but not higher

(39:18):
because they can go up to two TV. They can
go up to two TV. They could have found it
like below one fifteen. And also there's a window between
around like one fifty and one eight where it does
a very special thing. It turns into w bosons that
the tepatron would have been very good at finding. So
they were just you know, rolling the dice. If it
was low mass or if it was in this one window,

(39:40):
they totally would have found it. The tevatron would have
found the Higgs boson. So then what happened. Then they
gave up while they ran as long as they could,
and then once the l C turned on, then they
gave up. They said, all right, well there's no point anymore. Really, yeah,
what because I guess they weren't finding it. And so
they're like, all right, somebody has a better machine. Yeah,
And the LEDC is you know, ten times as powerful

(40:01):
as the tevatron has higher energy and more collisions per
second TV, So the LEDC is about five times is powerful.
It's collisions they varied from seven TV the start up
to now thirteen TV, so about an order of magnitude
more powerful. But also they have more collisions per second,
and so the tevatron knew that. You know, as soon

(40:22):
as it turned on it was going to find it
pretty quickly. There was no point to continue because but
the tevatron to find it would need like two and
a half times more data, need to run for like
another five or ten years. But you know there are
people in the fields who are like, no, we should
keep running, we should keep going because they might stumble, right, yeah,
they might crash right, Like the machine is hard to
get it to work. Yeah, And you know when they

(40:43):
turned the machine on the LHC after ten years they
had been quiet building this thing. They turned it on
in two thousand and eight. It only ran for like
nine days before there was a big disaster. So they
did stumble. They did stumble exactly, and there was an
electrical fault. One of the things hadn't been wired correctly,
and it's short at out and released like tons of
liquid helium. There's this big alarm. And I was actually

(41:05):
at the LHC that day. I was on shift in
the control room, which is normally a very boring thing.
You sit there, you look at a bunch of panels,
they're all green lights. You're trying not to fall asleep.
But sometimes something crazy happens. And that happened while I
was there. Really, like the lights turned red with the
big horns, like, yeah, exactly. Wasn't just like a computer

(41:26):
like a window popping up you just clicked Okay, You're like, wait, wait, wait,
what what did I say? No, it was a big disaster.
You know. There were fires and like really heavy equipment
got like shoved around inside the tunnel, and so it
was a big disaster. We got to hit the big
red button finally to you know, shut everything down. It
was exciting, but of course it was also disappointing because

(41:47):
it took like fifteen months to fix it. This stuff
is super cold, and so to fix it you have
to warm it up very gradually, fix it, and then
cool it down very gradually, which takes months and months.
So maybe the Teva try should have been going, you know,
so the Tabatron kept going during that window. They were like, oh,
we got one more little chance at this. They were
watching the L A C stumble yes exactly, and so

(42:09):
they were like, keep going, everybody, maybe we'll see it.
And so they pushed a little harder, one last gasp,
because again nobody knew where it was. It could have
been like just around the corner in the window that
tabatron could have found it. But in the end, the
LC turned on, and then people turned off the tabatron
because they figured they were not going to find it
was time to let the LC do its thing. And

(42:31):
pretty soon after it turned on, you guys found it.
Like it like, it didn't take a long time. It
didn't take a long time. You know. We turned on
again in like two thousand and ten and started analyzing data.
And you know, it takes a little bit of time
because you have to get enough data. And these colliders,
when you turn them on, they work and fits and
spurts until the engineers figure out like how to kick
it and how to tweak this knob, and you know,

(42:52):
on tuesdays you gotta elbow it this way and really
get it, you know, humming. But eventually the data started
pouring in and then we were doing that thing. We
were like pulling the water out of the swamp and
seeing the features, and you know, there were wiggles in
the data early on that people got excited about. And
people didn't know, is it there? Is it not there?
Where are we going to find it? Nobody really knew
where to look. So finally, one day, uh not on

(43:16):
July four, they actually started getting the data and and
it started to point to having found the Higgs. But
you know, was there a moment I imagine you told
me that maybe there wasn't, But I wonder if there
was a moment when like some grad student or some physicists,
you know, pulls out the data and they're like, huh,
what is this little bump? Well, you know there was
a moment for me in the summer of two thousand

(43:38):
and eleven. Both experiments saw bumps, but they saw bumps
in different places. Like ATLAS saw bump, but it was
at around a hundred and forty five g V. Cmsaw
bump around a hundred and twenty g V. So you
knew that they were just random because it didn't agree. Now,
these are two different experiments, ATLAS and CMS, two different
experiments at different points around the ring independent data, and

(43:59):
so you expect them if the Higgs is real, to
see bumps at the same place. It's a very important
cross check. And also the two groups. There's a whole
group of thousands of experimentalists working on ATLAS and thousands
of experimentalists working on CMS. They're not supposed to talk
to each other. It's supposed to keep each other separate.
It's supposed to keep these secrets so that the work
can be independent. The problem is, of course, all these

(44:21):
people know each other. We're all friends. Sometimes you got
like a married couple where one is on one experiment,
the others on the other experiment. You know, they're talking
to each other. So there's no way that any secrets
are really being kept. And so there was a moment
in like late two thousand eleven. I called up a
friend of mine on the other experiment. I said, hey, um,
you know we have a bump. Where's your bump? Had

(44:43):
a bump like I found? I found a lump? What no, no, no,
I mean sharing information like that is strictly against the rules.
I would never do that. Did I say it was me?
I mean, I'm in It was a colleague of mine
who talked to his friend and then and told me
about it. I mean, you must have misheard me. I
would never do that. You tainted the results. We had

(45:05):
this bump, and I was curious about whether they had
a bump, And it turns out they had a bump
in the same place. And that's the moment. And you
figured that out on the phone. At the moment I
started to believe when I thought, you know what, I
think this is it. I think we actually did find this. Daniel,
why did you do that? I think you mean my
colleague who broke them and your friend also broke it
because he told or she told you where the bump was. Again,

(45:28):
this is a story about a colleague of mine who
broke these rules. Everybody was breaking the rules. Man, these
were the worst kept secrets at certain Oh man, I
have less confidence now, Daniel in the Higgs Boson. Well,
I was not directly involved in producing that plot, so
it couldn't influence me in neither was he. Oh so
you were like literally a league like he learned some

(45:49):
secret and you you phone the other team again, this
unnamed colleague of mine, he was we saw bumps in
the same place, and so that's the moment I started
to believe it. And then we just kept collecting were
more data, and the bumps got bigger and bigger, and
they lined up right on top of each other. And
then in late June we had enough events, enough collisions
at all the same place that we could say, statistically

(46:12):
it was very, very unlikely for this to be random chance.
Random chance can produce anything, but the odds were like
one in millions that just random chance could produce all
these bumps that exactly the same place. So that was
the day we said, all right, we decided that now
we have discovered. And that was July four, And that
was j and there was big announcement at CERN, and

(46:35):
everybody knew it was gonna be the announcement the next day.
So starting like July three, everybody at CERN was like
standing in line to get into that auditorium and sleeping
in line, like camping out. You know, this is like
Comic Con, but Nerd edition at CERN and super conducting
super Nerds exactly, And people really wanted to be in
that room. And they invited Peter Higgs and he was

(46:57):
there and the director sir and give a tall talk,
and you know, for the people in the audience. We
are knew the results, we have been involved in producing
them and preparing them. But it was just a moment
we all got together and basically said, all right, let's
high five and declare that we have found this thing
after decades and decades of searching email. The rest of
the world is like the Higgs What wait, do you
have a collider in Geneva? Nobody told us about this.

(47:19):
You know, the team at certain is really good at PR.
They are very good at popularizing the science and making
people understand it. And that's why I think the Higgs
boson is one of the most famous particles is because
it's been well sold to the public as an exciting discovery. Also,
it was the Obama years. You know, we were we
were happy about all good years. That's right, and we
believed scientists. That's right. Then that gets us to today.

(47:41):
So now these days, we know that the Higgs field exists,
and that the Higgs boson exists, and it makes all
the equations balance out, and and now we have a
more complete picture of the yeiverse and the particles in it.
That's right. And now we know where the Higgs is.
It about a hundred and twenty five GV and number
we didn't know before we measured it, and we can
study all of its properties. We can see it turning
into this kind of particle in that kind of particle,

(48:03):
and we can try to measure its properties in great
detail and see is this the particle that Higgs predicted
or is it a weird version of it? Are there
more Higgs bosons out there? And so the search doesn't
stop just because we found it. Now we're studying in
gory detail and trying to see if it has any
more secrets to reveal. All right, well, again, also pretty
exciting and a good insight into how signs works little

(48:26):
by little through competition and friendly breaking of the rules.
And anybody on the Atlas Experiment who heard that, please
forgive me breaking the rules. But I bet you did too.
You're like, hopefully nobody's listening to this podcast, not a
couple of hundred thousand or ten thousand people. Well, I'm
sure you know there's like you know, podcast hosts, podcast

(48:49):
listener confidence reality. Absolutely, I mean we assume that, so
I'm trusting you with that story, folks. All right, Well,
thanks for joining us, Thanks for telling us a story.
Daniel We hope you enjoyed that. See you next time.
Thanks for listening, and remember that Daniel and Jorge Explain

(49:11):
the Universe is a production of I Heart Radio or
more podcast For my heart Radio, visit the I heart
Radio app, Apple Podcasts, or wherever you listen to your
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